Abiotic stress is a major threat to global crop yields and this problem is likely to be exacerbated in the future. Therefore, it is very important to engineer crop plants with improved stress tolerance. A large body of research has focussed on the immediate stress responses. However, in nature stress is frequently chronic or recurring, suggesting that temporal dynamics are an important, but under-researched, component of plant stress responses. Indeed, plants can be primed by a stress exposure such that they respond more efficiently to the next stress incident. Such stress priming and memory may be particularly beneficial to plants due to their sessile life style. Typically, the memory of priming lasts for several days after the end of the stress. During the past few years, my group has initiated the molecular analysis of heat stress memory in Arabidopsis thaliana. Heat stress memory is associated with sustained gene induction and transcriptional memory and we have demonstrated that this involves lasting chromatin changes. The underlying molecular mechanisms, however, remain poorly understood.
With climate change, losses in crop productivity are likely to become more severe. The exploitation of stress priming and memory for improving stress tolerance of crop plants holds great potential, because acute induction of stress tolerance mechanisms is often correlated with a reduction in growth due to reallocation of nutrients or as an adaptation to stress conditions.
In the CHROMADAPT project we combined mechanistic dissection of heat stress memory in A. thaliana with concomitant translation of the results into the temperate cereal crop barley. In particular, we focused on the following questions: How does chromatin structure affect and regulate heat stress memory? How do the transcription factors involved mediate memory-specific outputs? How do histone modifications during stress memory interact with transcription, chromatin and nuclear organization? Is heat stress memory conserved in temperate cereal species? Can we engineer plants with improved stress memory? Using existing tools and new methodologies, the analyses yielded unprecedented insight into the long-term adaptation of plants to abiotic stress and opened up strategies for breeding stress-tolerant crops.
